Typically used when 160 characters-or-less just won't cut it, four of the characters are used to write tlft and imply that the epic story will be conveyed in a higher-capacity medium e.g. vocally, electronically mailed (or "e-mailed"), instant messaged (IM'd), etc. One can also be slightly redundant in the same text and follow "tlft" with "tell you later."

Text 1: So what happened after you left the bar w/ that pornstar lookin chick?

Text 2: Well we got back to her place and started makin out. Then her roommate came home and... fuck man tlft, tell you when I see you later.

Text 3: Yea or I'm sure I'll read about it in Penthouse.

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Text 1: So what's this Unified Field Theory or whatever of yours again?